This Nonprovisional application claims priority under 35 U.S.C. xc2xa7119(a) on Patent Application No(s). 2002-248983 filed in JAPAN on Aug. 28, 2002, the entire contents of which are hereby incorporated by reference.
The present invention relates to a shared electrical/optical transmission equipment of a plug-and-jack type which is used for input and output in an audio device, an information terminal and the like. The invention also relates to an electronic device equipped with this transmission equipment.
Such a shared electrical/optical transmission equipment of a plug-and-jack type is provided in an electronic device such as an audio device or an information terminal, and is capable of receiving a round optical plug and a single-prong electrical plug. The shared electrical/optical transmission equipment has an insertion port which selectively receives either of a round optical plug or a single-prong electrical plug. With a round optical plug inserted, the transmission equipment exchanges an optical signal with an external device of the electronic device. With a single-prong electrical plug inserted, the transmission equipment establishes input/output paths for an electrical signal between an internal part of the electronic device and an external device.
For example, suppose that a shared electrical/optical transmission equipment of a plug-and-jack type is applied to an audio device. In this case, when a round optical plug or a single-prong electrical plug is selectively inserted in the insertion port of the shared electrical/optical transmission equipment, the transmission equipment can exchange an optical signal or can establish input/output paths for a digital or analog electrical signal.
In order to identify the type of plug inserted in the insertion hole, i.e. a round optical plug or a single-prong electrical plug, the shared electrical/optical transmission equipment of a plug-and-jack type contains a pair of identification terminals at the insertion port. If a single-prong electrical plug is inserted in the insertion port, the plug pushes the identification terminals and establishes mutual contact between them. On the other hand, a round optical plug inserted in the insertion port does not cause such mutual contact. Thus, the plug type can be identified, depending on whether the identification terminals are in mutual contact or not. For reliable plug identification, the contact resistance between the identification terminals should be kept at 30 mxcexa9 or below when they are in contact with each other. This is done by plating the identification terminals with silver.
Nevertheless, while a silver plate is left in the atmosphere, sulfuration proceeds at its surface. Hence, if a shared electrical/optical transmission equipment is left without being mounted on the substrate of an electronic device, the surfaces of the silver-plated identification terminals undergo sulfuration. On the one hand, sulfuration deteriorates solderability at the surfaces of the silver-plated identification terminals, making it impossible to mount the transmission equipment on the substrate of an electronic device. On the other hand, sulfuration results in increase of the contact resistance between the identification terminals, in which case reliable plug identification cannot be expected.
The present invention is made in light of these conventional problems, and intends to provide a shared electrical/optical transmission equipment of a plug-and-jack type which prevents deterioration in solderability of the identification terminals and which avoids increase of the contact resistance between the identification terminals, even if the transmission equipment is left in the atmosphere. In addition, the present invention intends to provide an electronic device equipped with this transmission equipment.
To solve the above problems, the present invention is concerned with a shared electrical and optical transmission equipment of a plug-and-jack type at least comprising a main body which contains an insertion port for selectively receiving either of a round optical plug or a single-prong electrical plug, an optical semiconductor chip which exchanges an optical signal with a round optical plug inserted in the insertion port of the main body, at least one terminal which makes electrical contact with a single-prong electrical plug inserted in the insertion port of the main body, a pair of identification terminals which make mutual contact when pushed by either of the round optical plug or the single-prong electrical plug inserted in the insertion port of the main body. In this transmission equipment, each of the pair of identification terminals has a connection portion to connect to an external device as well as a contact portion to make contact with the other identification terminal. The connection portion is plated at least with solder, and the contact portion is plated with gold.
According to the present invention of this arrangement, each of the identification terminals has a connection portion to connect to an external device as well as a contact portion to make contact with the other identification terminal. The connection portion is plated at least with solder, whereas the contact portion is plated with gold in addition to solder. As a result, even if the shared electrical/optical transmission equipment is left in the atmosphere, the solder-plated connection portions of the identification terminals do not deteriorate in solderability. Besides, since the gold plates undergo neither sulfuration nor oxidation while left in the atmosphere, it is possible to avoid increase of the contact resistance between the gold-plated contact portions of the identification terminals.
In the present invention, each of the pair of identification terminals may be entirely plated with solder, and additionally plated with gold exclusively at the contact portion. The gold plate may be a flash plate. Since gold plating is applied to the surface of the solder plate, it is possible to decrease the thickness of a gold-plated layer and thereby to reduce the amount of gold required.
Further in the present invention, a value of resistance between the identification terminals may be 30 mxcexa9 or below when they are in contact with each other.
With the value of resistance between the identification terminals being set in this range, the transmission equipment can reliably identify which of a round optical plug or a single-prong electrical plug is inserted in the insertion port.
In addition, an electronic device of the present invention is equipped with a shared electrical/optical transmission equipment of a plug-and-jack type according to the present invention.
In other words, the present invention is not limited to a shared electrical/optical transmission equipment of a plug-and-jack type, but further encompasses an electronic device which adopts this plug-and-jack type shared electrical/optical transmission equipment. The electronic device may be of any kind as far as being adapted for input and output of an optical signal and an electrical signal. As such, there may be mentioned reproducing apparatus, image receiver and the like, including audio devices, DVD players, VTRs and CD players.